Volley的優(yōu)缺點(diǎn)
優(yōu)點(diǎn)
- 自動(dòng)的調(diào)度網(wǎng)絡(luò)請(qǐng)求
- 多并發(fā)的網(wǎng)絡(luò)請(qǐng)求
- 可以緩存http請(qǐng)求
- 支持請(qǐng)求的優(yōu)先級(jí)
- 支持取消請(qǐng)求的API缸逃，可以取消單個(gè)請(qǐng)求，可以設(shè)置取消請(qǐng)求的范圍域瓤狐。
- 代碼標(biāo)準(zhǔn)化榜配，使開發(fā)者更容易專注于我們的業(yè)務(wù)的邏輯處理
- 更容易給UI填充來自網(wǎng)絡(luò)請(qǐng)求的數(shù)據(jù)
- Volley可以是作為調(diào)試和跟蹤的工具（用起來特別爽~）
缺點(diǎn)
- 使用的是httpclient、HttpURLConnection
- 6.0不支持httpclient了盖袭，如果想支持得添加org.apache.http.legacy.jar
- 非常不適合大的文件流操作，例如上傳和下載彼宠。因?yàn)閂olley會(huì)把所有的服務(wù)器端返回的數(shù)據(jù)在解析期間緩存進(jìn)內(nèi)存鳄虱。
- 只支持http請(qǐng)求
- 圖片加載性能一般
Volley的工作原理
源碼解析
下面開始Volley源碼解析，為了方便理解凭峡，我們按照Volley的實(shí)際開發(fā)使用流程來分析其源碼拙已。
（1）初始化RequestQueue
- 按照Volley的使用方法，我們最先開始要初始化一個(gè)RequestQueue摧冀，由于新建一個(gè)RequestQueue非常消耗資源倍踪，開發(fā)的時(shí)候只需創(chuàng)建一次即可
RequestQueue queue = Volley.newRequestQueue(getApplicationContext());
- 接著會(huì)執(zhí)行Volley這個(gè)類的newRequestQueue方法
public static RequestQueue newRequestQueue(Context context, BaseHttpStack stack) {
BasicNetwork network;
if (stack == null) {
if (Build.VERSION.SDK_INT >= 9) {
network = new BasicNetwork(new HurlStack());
} else {
String userAgent = "volley/0";
try {
String packageName = context.getPackageName();
PackageInfo info = context.getPackageManager().getPackageInfo(packageName, 0);
userAgent = packageName + "/" + info.versionCode;
} catch (NameNotFoundException e) {
}
network = new BasicNetwork(
new HttpClientStack(AndroidHttpClient.newInstance(userAgent)));
}
} else {
network = new BasicNetwork(stack);
}
return newRequestQueue(context, network);
}
上面源碼可以看出，如果Android版本大于或等于2.3索昂，則調(diào)用給予HttpURLCollection的HurlStack建车，否則就調(diào)用HttpClient的HttpClientStack，接下來Volley會(huì)創(chuàng)建RequestQueue椒惨，并調(diào)用它的start方法缤至。
public void start() {
stop(); // Make sure any currently running dispatchers are stopped.
// Create the cache dispatcher and start it.
mCacheDispatcher = new CacheDispatcher(mCacheQueue, mNetworkQueue, mCache, mDelivery);
mCacheDispatcher.start();
// Create network dispatchers (and corresponding threads) up to the pool size.
for (int i = 0; i < mDispatchers.length; i++) {
NetworkDispatcher networkDispatcher = new NetworkDispatcher(mNetworkQueue, mNetwork,
mCache, mDelivery);
mDispatchers[i] = networkDispatcher;
networkDispatcher.start();
}
}
RequestQueue對(duì)象創(chuàng)建的時(shí)候，會(huì)初始化一個(gè)緩存調(diào)度線程（CacheDispatcher）康谆，和4個(gè)網(wǎng)絡(luò)調(diào)度線程(NetworkDispatcher)领斥，所以Volley默認(rèn)會(huì)在后臺(tái)開啟5個(gè)線程。線程都初始化之后沃暗，分別調(diào)用其start方法開啟線程月洛。
（2） 把Request請(qǐng)求添加進(jìn)RequestQueue請(qǐng)求隊(duì)列之后的流程
queue.add(stringRequest);
- 把 Request請(qǐng)求添加進(jìn)RequestQueue中，首先通過執(zhí)行request.shouldCache()方法判斷request是否應(yīng)該緩存孽锥，默認(rèn)情況下是true嚼黔，也就是所有的請(qǐng)求默認(rèn)都要緩存。如果request不需要緩存的話惜辑，把請(qǐng)求放進(jìn)網(wǎng)絡(luò)請(qǐng)求隊(duì)列隔崎，如果request需要緩存那就放進(jìn)緩存隊(duì)列。
public <T> Request<T> add(Request<T> request) {
// Tag the request as belonging to this queue and add it to the set of current requests.
request.setRequestQueue(this);
synchronized (mCurrentRequests) {
mCurrentRequests.add(request);
}
// Process requests in the order they are added.
request.setSequence(getSequenceNumber());
request.addMarker("add-to-queue");
// If the request is uncacheable, skip the cache queue and go straight to the network.
if (!request.shouldCache()) {
mNetworkQueue.add(request);
return request;
}
mCacheQueue.add(request);
return request;
}
** RequestQueue的add方法并沒有進(jìn)行網(wǎng)絡(luò)或?qū)彺娴牟僮髟铣螅?dāng)請(qǐng)求添加金網(wǎng)絡(luò)請(qǐng)求隊(duì)列或者緩存隊(duì)列時(shí)爵卒，在后臺(tái)的網(wǎng)絡(luò)調(diào)度線程和緩存調(diào)度線程會(huì)輪詢各自的請(qǐng)求隊(duì)列，如果發(fā)現(xiàn)請(qǐng)求任務(wù)需要處理則開始執(zhí)行撵彻。下面分別來分析CacheDispatcher和NetworkDispatcher的源碼钓株。**
（3）CacheDispatcher的工作流程
- CacheDispatcher線程的run方法里是一個(gè)死循環(huán)实牡，并不斷地執(zhí)行processRequest方法
@Override public void run() {
if (DEBUG) VolleyLog.v("start new dispatcher");
Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND); // Make a blocking call to initialize the cache.
mCache.initialize(); while (true) {
try {
processRequest();
} catch (InterruptedException e) {
// We may have been interrupted because it was time to quit.
if (mQuit) {
return;
}
}
}
}
- CacheDispatcher線程的processRequest方法
private void processRequest() throws InterruptedException {
// Get a request from the cache triage queue, blocking until
// at least one is available.
final Request<?> request = mCacheQueue.take();
request.addMarker("cache-queue-take");
// If the request has been canceled, don't bother dispatching it.
if (request.isCanceled()) {
request.finish("cache-discard-canceled");
return;
}
// Attempt to retrieve this item from cache.
Cache.Entry entry = mCache.get(request.getCacheKey());
if (entry == null) {
request.addMarker("cache-miss");
// Cache miss; send off to the network dispatcher.
if (!mWaitingRequestManager.maybeAddToWaitingRequests(request)) {
mNetworkQueue.put(request);
}
return;
}
// If it is completely expired, just send it to the network.
if (entry.isExpired()) {
request.addMarker("cache-hit-expired");
request.setCacheEntry(entry);
if (!mWaitingRequestManager.maybeAddToWaitingRequests(request)) {
mNetworkQueue.put(request);
}
return;
}
// We have a cache hit; parse its data for delivery back to the request.
request.addMarker("cache-hit");
Response<?> response = request.parseNetworkResponse(
new NetworkResponse(entry.data, entry.responseHeaders));
request.addMarker("cache-hit-parsed");
if (!entry.refreshNeeded()) {
// Completely unexpired cache hit. Just deliver the response.
mDelivery.postResponse(request, response);
} else {
// Soft-expired cache hit. We can deliver the cached response,
// but we need to also send the request to the network for
// refreshing.
request.addMarker("cache-hit-refresh-needed");
request.setCacheEntry(entry);
// Mark the response as intermediate.
response.intermediate = true;
if (!mWaitingRequestManager.maybeAddToWaitingRequests(request)) {
// Post the intermediate response back to the user and have
// the delivery then forward the request along to the network.
mDelivery.postResponse(request, response, new Runnable() {
@Override
public void run() {
try {
mNetworkQueue.put(request);
} catch (InterruptedException e) {
// Restore the interrupted status
Thread.currentThread().interrupt();
}
}
});
} else {
// request has been added to list of waiting requests
// to receive the network response from the first request once it returns.
mDelivery.postResponse(request, response);
}
}
}
可以發(fā)現(xiàn)該方法如果請(qǐng)求被取消的話，退出該方法轴合；如果請(qǐng)求沒有被取消則判斷請(qǐng)求是否有緩存的響應(yīng)创坞。如果有緩存的響應(yīng)并且沒有過期，則對(duì)緩存響應(yīng)進(jìn)行解析并回調(diào)給主線程受葛；如果沒有緩存的響應(yīng)题涨，則將請(qǐng)求加入網(wǎng)絡(luò)隊(duì)列，接下來看看網(wǎng)絡(luò)調(diào)度線程N(yùn)etworkDispatcher是如何工作的总滩。
（4）NetworkDispatcher的工作流程
- NetworkDispatcher的run方法同樣也會(huì)執(zhí)行processRequest方法纲堵，如下所示：
@Override
public void run() {
Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
while (true) {
try {
processRequest();
} catch (InterruptedException e) {
// We may have been interrupted because it was time to quit.
if (mQuit) {
return;
}
}
}
}
processRequest方法如下所示：
private void processRequest() throws InterruptedException {
// Take a request from the queue.
Request<?> request = mQueue.take();
long startTimeMs = SystemClock.elapsedRealtime();
try {
request.addMarker("network-queue-take");
// If the request was cancelled already, do not perform the
// network request.
if (request.isCanceled()) {
request.finish("network-discard-cancelled");
request.notifyListenerResponseNotUsable();
return;
}
addTrafficStatsTag(request);
// Perform the network request.
NetworkResponse networkResponse = mNetwork.performRequest(request);
request.addMarker("network-http-complete");
// If the server returned 304 AND we delivered a response already,
// we're done -- don't deliver a second identical response.
if (networkResponse.notModified && request.hasHadResponseDelivered()) {
request.finish("not-modified");
request.notifyListenerResponseNotUsable();
return;
}
// Parse the response here on the worker thread.
Response<?> response = request.parseNetworkResponse(networkResponse);
request.addMarker("network-parse-complete");
// Write to cache if applicable.
// TODO: Only update cache metadata instead of entire record for 304s.
if (request.shouldCache() && response.cacheEntry != null) {
mCache.put(request.getCacheKey(), response.cacheEntry);
request.addMarker("network-cache-written");
}
// Post the response back.
request.markDelivered();
mDelivery.postResponse(request, response);
request.notifyListenerResponseReceived(response);
} catch (VolleyError volleyError) {
volleyError.setNetworkTimeMs(SystemClock.elapsedRealtime() - startTimeMs);
parseAndDeliverNetworkError(request, volleyError);
request.notifyListenerResponseNotUsable();
} catch (Exception e) {
VolleyLog.e(e, "Unhandled exception %s", e.toString());
VolleyError volleyError = new VolleyError(e);
volleyError.setNetworkTimeMs(SystemClock.elapsedRealtime() - startTimeMs);
mDelivery.postError(request, volleyError);
request.notifyListenerResponseNotUsable();
}
}
網(wǎng)絡(luò)調(diào)度線程也是不斷地從隊(duì)列中取出請(qǐng)求并且判斷該請(qǐng)求是否被取消了。如果該請(qǐng)求沒有被取消闰渔，就去請(qǐng)求網(wǎng)絡(luò)席函，并把網(wǎng)絡(luò)請(qǐng)求的數(shù)據(jù)回調(diào)回主線程。請(qǐng)求網(wǎng)絡(luò)時(shí)調(diào)用Network的performRequest()方法冈涧，下面看看Network的這個(gè)類的performRequest方法茂附。
@Override
public NetworkResponse performRequest(Request<?> request) throws VolleyError {
long requestStart = SystemClock.elapsedRealtime();
while (true) {
HttpResponse httpResponse = null;
byte[] responseContents = null;
List<Header> responseHeaders = Collections.emptyList();
try {
// Gather headers.
Map<String, String> additionalRequestHeaders =
getCacheHeaders(request.getCacheEntry());
httpResponse = mBaseHttpStack.executeRequest(request, additionalRequestHeaders);
int statusCode = httpResponse.getStatusCode();
responseHeaders = httpResponse.getHeaders();
// Handle cache validation.
if (statusCode == HttpURLConnection.HTTP_NOT_MODIFIED) {
Entry entry = request.getCacheEntry();
if (entry == null) {
return new NetworkResponse(HttpURLConnection.HTTP_NOT_MODIFIED, null, true,
SystemClock.elapsedRealtime() - requestStart, responseHeaders);
}
// Combine cached and response headers so the response will be complete.
List<Header> combinedHeaders = combineHeaders(responseHeaders, entry);
return new NetworkResponse(HttpURLConnection.HTTP_NOT_MODIFIED, entry.data,
true, SystemClock.elapsedRealtime() - requestStart, combinedHeaders);
}
// Some responses such as 204s do not have content. We must check.
InputStream inputStream = httpResponse.getContent();
if (inputStream != null) {
responseContents =
inputStreamToBytes(inputStream, httpResponse.getContentLength());
} else {
// Add 0 byte response as a way of honestly representing a
// no-content request.
responseContents = new byte[0];
}
// if the request is slow, log it.
long requestLifetime = SystemClock.elapsedRealtime() - requestStart;
logSlowRequests(requestLifetime, request, responseContents, statusCode);
if (statusCode < 200 || statusCode > 299) {
throw new IOException();
}
return new NetworkResponse(statusCode, responseContents, false,
SystemClock.elapsedRealtime() - requestStart, responseHeaders);
} catch (SocketTimeoutException e) {
attemptRetryOnException("socket", request, new TimeoutError());
} catch (MalformedURLException e) {
throw new RuntimeException("Bad URL " + request.getUrl(), e);
} catch (IOException e) {
int statusCode;
if (httpResponse != null) {
statusCode = httpResponse.getStatusCode();
} else {
throw new NoConnectionError(e);
}
VolleyLog.e("Unexpected response code %d for %s", statusCode, request.getUrl());
NetworkResponse networkResponse;
if (responseContents != null) {
networkResponse = new NetworkResponse(statusCode, responseContents, false,
SystemClock.elapsedRealtime() - requestStart, responseHeaders);
if (statusCode == HttpURLConnection.HTTP_UNAUTHORIZED ||
statusCode == HttpURLConnection.HTTP_FORBIDDEN) {
attemptRetryOnException("auth",
request, new AuthFailureError(networkResponse));
} else if (statusCode >= 400 && statusCode <= 499) {
// Don't retry other client errors.
throw new ClientError(networkResponse);
} else if (statusCode >= 500 && statusCode <= 599) {
if (request.shouldRetryServerErrors()) {
attemptRetryOnException("server",
request, new ServerError(networkResponse));
} else {
throw new ServerError(networkResponse);
}
} else {
// 3xx? No reason to retry.
throw new ServerError(networkResponse);
}
} else {
attemptRetryOnException("network", request, new NetworkError());
}
}
}
}
可以發(fā)現(xiàn)通過mBaseHttpStack的executeRequest方法返回響應(yīng)的數(shù)據(jù)，其實(shí)mBaseHttpStack就是前面提的HulStack和HttpClientStack的父類督弓∮回到NetworkDispatcher請(qǐng)求網(wǎng)絡(luò)后，會(huì)將響應(yīng)結(jié)果存在緩存中愚隧，并調(diào)用下面這段代碼Delivery的postResponse方法溶推。如下所示
mDelivery.postResponse(request, response);
@Override
public void postResponse(Request<?> request, Response<?> response, Runnable runnable) {
request.markDelivered();
request.addMarker("post-response");
mResponsePoster.execute(new ResponseDeliveryRunnable(request, response, runnable));
}
ResponseDeliveryRunnable里面做了什么：
@SuppressWarnings("unchecked")
@Override
public void run() {
// NOTE: If cancel() is called off the thread that we're currently running in (by
// default, the main thread), we cannot guarantee that deliverResponse()/deliverError()
// won't be called, since it may be canceled after we check isCanceled() but before we
// deliver the response. Apps concerned about this guarantee must either call cancel()
// from the same thread or implement their own guarantee about not invoking their
// listener after cancel() has been called.
// If this request has canceled, finish it and don't deliver.
if (mRequest.isCanceled()) {
mRequest.finish("canceled-at-delivery");
return;
}
// Deliver a normal response or error, depending.
if (mResponse.isSuccess()) {
mRequest.deliverResponse(mResponse.result);
} else {
mRequest.deliverError(mResponse.error);
}
// If this is an intermediate response, add a marker, otherwise we're done
// and the request can be finished.
if (mResponse.intermediate) {
mRequest.addMarker("intermediate-response");
} else {
mRequest.finish("done");
}
// If we have been provided a post-delivery runnable, run it.
if (mRunnable != null) {
mRunnable.run();
}
}
上面代碼可以看到如果響應(yīng)成功將會(huì)執(zhí)行Request的deliverResponse方法，并把響應(yīng)結(jié)果傳進(jìn)去奸攻，如果響應(yīng)失敗，就執(zhí)行deliverError方法虱痕，并把響應(yīng)失敗的對(duì)象傳進(jìn)去睹耐。接著我們就看看Request的deliverResponse都干了什么。Request的子類有很多部翘，這里就拿StringRequest來做參考硝训。
@Override
protected void deliverResponse(String response) {
Response.Listener<String> listener;
synchronized (mLock) {
listener = mListener;
}
if (listener != null) {
listener.onResponse(response);
}
}
錯(cuò)誤的回調(diào)在父類Request中可以找到
public void deliverError(VolleyError error) {
Response.ErrorListener listener;
synchronized (mLock) {
listener = mErrorListener;
}
if (listener != null) {
listener.onErrorResponse(error);
}
}
拿到響應(yīng)結(jié)果之后，如果請(qǐng)求成功則回調(diào)onResponse
新思，如果請(qǐng)求失敗則回調(diào)onErrorResponse窖梁，整個(gè)流程就是這樣了。
源碼中涉及到的一些知識(shí)點(diǎn)
（1）Volley是如何把請(qǐng)求的數(shù)據(jù)回調(diào)回主線程中的夹囚？
使用Handler.postRunnable（Runnable）方法回調(diào)回主線程中進(jìn)行處理纵刘，ExecutorDelivery的構(gòu)造方法中可以看到這段代碼，如下所示：
public ExecutorDelivery(final Handler handler) {
// Make an Executor that just wraps the handler.
mResponsePoster = new Executor() {
@Override
public void execute(Runnable command) {
handler.post(command);
}
};
}
(2)Volley開啟了幾個(gè)后臺(tái)線程荸哟？
總共開啟了5個(gè)線程：1個(gè)緩存調(diào)度線程和4個(gè)網(wǎng)絡(luò)調(diào)度線程假哎，并且線程的優(yōu)先級(jí)為10瞬捕，即后臺(tái)線程。Volley其實(shí)并沒有開啟線程池去維護(hù)線程舵抹，而是硬性地開了5個(gè)線程肪虎，這點(diǎn)我覺得是可以進(jìn)行優(yōu)化的。
Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
（3）Volley進(jìn)行網(wǎng)絡(luò)請(qǐng)求時(shí)用到了Http協(xié)議的哪些字段惧蛹？
響應(yīng)的數(shù)據(jù)解析在HttpHeaderParser類中的parseCacheHeaders方法中可以找到
public static Cache.Entry parseCacheHeaders(NetworkResponse response) {
long now = System.currentTimeMillis();
Map<String, String> headers = response.headers;
long serverDate = 0;
long lastModified = 0;
long serverExpires = 0;
long softExpire = 0;
long finalExpire = 0;
long maxAge = 0;
long staleWhileRevalidate = 0;
boolean hasCacheControl = false;
boolean mustRevalidate = false;
String serverEtag = null;
String headerValue;
headerValue = headers.get("Date");
if (headerValue != null) {
serverDate = parseDateAsEpoch(headerValue);
}
headerValue = headers.get("Cache-Control");
if (headerValue != null) {
hasCacheControl = true;
String[] tokens = headerValue.split(",");
for (int i = 0; i < tokens.length; i++) {
String token = tokens[i].trim();
if (token.equals("no-cache") || token.equals("no-store")) {
return null;
} else if (token.startsWith("max-age=")) {
try {
maxAge = Long.parseLong(token.substring(8));
} catch (Exception e) {
}
} else if (token.startsWith("stale-while-revalidate=")) {
try {
staleWhileRevalidate = Long.parseLong(token.substring(23));
} catch (Exception e) {
}
} else if (token.equals("must-revalidate") || token.equals("proxy-revalidate")) {
mustRevalidate = true;
}
}
}
headerValue = headers.get("Expires");
if (headerValue != null) {
serverExpires = parseDateAsEpoch(headerValue);
}
headerValue = headers.get("Last-Modified");
if (headerValue != null) {
lastModified = parseDateAsEpoch(headerValue);
}
serverEtag = headers.get("ETag");
// Cache-Control takes precedence over an Expires header, even if both exist and Expires
// is more restrictive.
if (hasCacheControl) {
softExpire = now + maxAge * 1000;
finalExpire = mustRevalidate
? softExpire
: softExpire + staleWhileRevalidate * 1000;
} else if (serverDate > 0 && serverExpires >= serverDate) {
// Default semantic for Expire header in HTTP specification is softExpire.
softExpire = now + (serverExpires - serverDate);
finalExpire = softExpire;
}
Cache.Entry entry = new Cache.Entry();
entry.data = response.data;
entry.etag = serverEtag;
entry.softTtl = softExpire;
entry.ttl = finalExpire;
entry.serverDate = serverDate;
entry.lastModified = lastModified;
entry.responseHeaders = headers;
entry.allResponseHeaders = response.allHeaders;
return entry;
}
用到的Http協(xié)議的字段如下：
Date：返回服務(wù)器時(shí)間扇救，如果想得到服務(wù)器的時(shí)候，我們可以從這里獲取
Cache-Control:為no-cache和no-store:不緩存響應(yīng)數(shù)據(jù)香嗓，如果需要緩存響應(yīng)數(shù)據(jù)迅腔，當(dāng)需要設(shè)置緩存時(shí)，通過maxAge的值來設(shè)置緩存過期的時(shí)間陶缺。
Must-revalidate和proxy-revalidate：該值為一個(gè)boolean值钾挟，服務(wù)器告訴客戶端，緩存數(shù)據(jù)過期前饱岸，可以使用緩存掺出；緩存一旦過期，必須去源服務(wù)器進(jìn)行有效性校驗(yàn)苫费。
Expires:設(shè)置緩存過期的時(shí)間汤锨，如果 Cache-Control設(shè)置為需要緩存，那么優(yōu)先以 Cache-Control的maxAge的值來設(shè)置緩存過期時(shí)間百框。
Last-Modified：在瀏覽器第一次請(qǐng)求某一個(gè)URL時(shí)闲礼，服務(wù)器端的返回狀態(tài)會(huì)是200，內(nèi)容是客戶端請(qǐng)求的資源铐维，同時(shí)有一個(gè)Last-Modified的屬性標(biāo)記此文件在服務(wù)器端最后被修改的時(shí)間柬泽。
客戶端第二次請(qǐng)求此URL時(shí)，根據(jù)HTTP協(xié)議的規(guī)定嫁蛇，瀏覽器會(huì)向服務(wù)器傳送If-Modified-Since報(bào)頭锨并，詢問該時(shí)間之后文件是否有被修改過，如果服務(wù)器端的資源沒有變化睬棚，則自動(dòng)返回 HTTP 304（Not Changed.）狀態(tài)碼第煮，內(nèi)容為空，這樣就節(jié)省了傳輸數(shù)據(jù)量抑党。它和請(qǐng)求頭的if-modified-since字段去判斷資源有沒有被修改的包警。ETags:它和if-None-Match(HTTP協(xié)議規(guī)格說明定義ETag為“被請(qǐng)求變量的實(shí)體值”，或者是一個(gè)可以與Web資源關(guān)聯(lián)的記號(hào))常用來判斷當(dāng)前請(qǐng)求資源是否改變底靠。類似于Last-Modified和HTTP-IF-MODIFIED-SINCE害晦。但是有所不同的是Last-Modified和HTTP-IF-MODIFIED-SINCE只判斷資源的最后修改時(shí)間，而ETags和If-None-Match可以是資源任何的任何屬性暑中，不如資源的MD5等篱瞎。
關(guān)于Volley的其它用法苟呐，可以參照我之前寫的幾篇文章
Volley的基本使用方法
Volley的封裝
那些年我使用Volley遇到的坑
好的就這些了，如果對(duì)你有用記得點(diǎn)個(gè)贊表示小小的鼓勵(lì)一下俐筋。
